Any place to base tune a 125 in the ATL area

Had my RS125 for a little over a year and still trying to come to terms with tuning it. Several sacrificed plugs and one piston in the process.
I'm trying to find a shop that could do a base tune on the bike and work from there. I had talked to Huey from MM at Barber, but he said he wasn't to hot on tuning two strokes. He directed me to reach out to Rocky here on the forum, but he hasn't been on the board for quite some time.

Would anyone know of a good shop that could do a base tune for the bike? I'm in the North Atlanta area. Trying to stay with in a 5 hr drive if possible, but closer is better.

Or if someone has a way to contact Rocky aka TwoCycler outside of the forum, could you let me know.

Thanks!

 

There is tons of tech data online on the RS125. Honda publishes all the tuning manuals. The base set ups in the tuning manuals are very good and should get you close depending on the configuration of your bike. But, there are lots to consider as the information in the tuning manuals is year and configuration specific. If you have a hodge podge of parts it might be more difficult.

The bases given in the tuning manuals are listed with the specific weather conditions. The manual goes on to tell you how to calculate the correction factors for changing weather conditions. Very helpful. With a little effort you can build spread sheet that spits out the correct main jet size based upon current weather conditions, given you have a good base line.

Contact me offline and I can help you out. My experience comes from tuning my TZ250 over the past 8 years and my girlfriends RS125. I'm also a rocket scientist.

Also, a great resource is the tech forums at USGPRU.net and the tech data at RScycles.com

Eric

 

Thanks for the input Eric. I think I have pretty much gone through all the Honda manuals, and spent months reading the USGPRU forums. I might just be a case of information overload. After melting down a piston and coming close to loosing a cylinder I started thinking to find a shop to help set a baseline.

Last time out at Barber I was planning on trying plug chops there. But Barber isn't a great track for plug chops. Also my bike does seem to be a mix of parts. 98 bike with 02 motor. VHM 11.6 head instert and the cylinder appears to be ported,or at least had some work done to it.

Definitely could use help on what to focus on for tuning. I'll shoot you a PM.

 

Contact Charlie at HFD1. www.hfd1motorsports.com. I am certain he could assist..

 

Fatbaq.com

 

Kerry Kling at Augusta Speed Shop in Augusta, GA.

I've ran a bone stock '98 RS125 for the past 4 years and have had a blast. I don't know about inserts and head volumes (well I know about them, but have never worked with them), but I know that the chance of riding it so well that you need to start getting high performance stuff or tuning to different tracks is very slim. Learning how to ride it is way more effective than trying to hot rod it. I go middle of the road settings (using info that Eric referenced above, and that it sounds like you have) and I've never had a problem.

Are you running leaded or unleaded set up? Do have have a feel for the jetting yet?

I would be happy to talk with you about it also. I'll be at a lot of the SE/Coastal events, and probably several of the USGPRU events in the area, as work/family schedule allows. I'm shooting for RRR in a couple of weeks if you are going to that.

Matt

 

Thanks, I'll talk with him and get a feel of his confidence on tuning two strokes.

One thing I totally appreciated with Huey, he was straight up that he was not confident in tuning them.

Bookmarked thanks!

 

I'm shooting for just getting a mild tune on it and trying to find a good baseline to work from. Thought I had a feel for the jetting until I melted down a piston. The bike is set to run unleaded. Was running C10. Had a discussion with the VP guy out in Commerce. Told him the requirements from the manual, he recommended C9. While trying to rejet for that fuel is when I melted the piston down. Got the bike back up and running was going to try to rejet again at Barber. But was hard to do plug chops there, so just threw in the biggest jet I had and called it a day. The bike did fine on the C9, just ended up with a black/wet plug from it.

Truly my head is in information overload on what variables are best track, or the easiest to track. Humidity vs Dew point, air density vs relative air density vs barometric pressure vs altitude. Seems many people have different ways to skin this cat. Looking at the jetting calculator on Fatbaq.com they are just using temp, altitude and humidity. Maybe those are the items to track. I have a handheld hiking weather station that calculates RAD, and I was trying to work with that. But I do not have a 100% confidence in it yet.

I was going to try and make the RRR round. Just got to get the bike back together after going through all the suspension and wheel bearings. I do need to go through the new riders school. I can see trying to tune the bike and do the school being a giant PIA. If it does pan out on making it there, I'll reach out to you.

 

Use the fatbaq charts. Run C12 at 20:1. Do not change fuel or oil types. I used Honda synthetic. The only time I had a top end failure, using a cheap weather station, was when I foolishly tried a wossner piston. If you are off by one jet size either way, there will be a slight difference in power characteristics but you will not harm the motor. You will soon be able to jet with just a glance at your weather station. It's not as complicated as people make it out to be.

 

What Nigel said. I have a jet-temp-humidity chart in Farenheit and maybe by luck based on my setup (I have an airbox) the chart is typically about the top of the '3-jet range' that all work fine. I run C12 at 20:1 using the Motul double ester oil. If you wanted to convert to leaded, there might be a few things you have to do, or could do, to get the setup - maybe the needle, maybe leaded ECU is different, ??? I'm sure there is info on USGPRU on that. I don't know of anybody running unleaded now.

I don't even have a RAD gauge or a nice weather station... In the morning, just look up the temp and humidity (can even check a nearby weather station with an app on your phone if you have forgotten your $10 weather station - like when a kid takes it out of your trailer for a school project... :| ), put in the jet, and probably don't change it all day. I know the jet is a little fat when coming off a corner, it might stumble a little and I have to feather (or worst case, pump) the throttle to clear it out. Then I just drop down a jet or two if it is going to be hot that day. I'm always between 170 or 175 unless it is really hot (Road Atlanta, RRR in summer) or if it is nice and cool and dry. I thought about getting a RAD gauge and plotting jets, etc. but honestly, I just want to have fun and not work on it too much. I don't want to get into det counters, head inserts, carbon fiber reeds, etc. etc. They can be VERY simple.

 

Nigel / Nanthala, thanks for the input.

Maybe coincidence or not, the piston that did melted down was a Wossner. I have a HRC in it now and no issues at Barber. From what I have read people have mixed luck with them. But this was awhile ago so took it with a grain of salt. Maybe that was my down fall giving it a try to save $30. Finding more current experiences online is getting harder to come by as less people are racing them, so trying some things on my own. Live and learn.

For changing over to leaded, from what I understand, is mainly jetting changes. Also you can change the head volume and ECU if you want. But the last too don't seem critical for unleaded to leaded switch over.

I'm hoping to get to the simple stage where you are Nantahala. Hell, I have a friend in CA that ran pump gas in his before he knew better. He never had an issue.

 

Dragstrip.

 

We always ran leaded. I had a friend that tried unleaded for awhile and then switched back. We were usually between 168 and 172 mains. I think the main needle we used ended in 68. The unleaded needles are different then the leaded.

 

That would be entertaining. I'll bet you could use every spare clutch plate in north america in one day.

 

If you want to use a dragstrip as a dyno, just launch like you're leaving McDonald's. It's what you do on a roller dyno, right? Hit the button at 4K RPM?

It's not necessary to launch it like a rocket at the dragstrip, just take off consistently. You're looking for trap speed, that'll get you your main for power. From there, concentrate on your 1/8m to play with the needle, where you're pulling at RPM that simulates running on a road course.
Dynos lie, clocks don't.

Take it FWIW, I had a friend "dyno" an air-cooled 2T at a dragstrip. Wanting to confirm he made the right jetting choices, he took it to a dyno guy. The dyno guy squeaked out a bunch more HP!
But when my friend hit the track, the bike was a dog - would not pull and fell on its face on top. He went back to his strip-dynoed jetting and all was well again.

Many ways to skin a cat...some better than others, depending on the cat.

 

Paul Hoyt-Nelson switched to unleaded in his RS125. He probably had a det counter and exhaust gas temp plugged into a Honda data logger to keep an eye on things. Certainly, it can be done, but I know he spent a lot of time getting things setup. Search over on the USGRPU forum - I think he wrote up what he did.

I've thought of switching, but Sunoco 110 leaded is readily available at tracks and my bikes were already setup for leaded - why make more work for myself!

Only times I've had issues with seizing have been due to a bad seal - unfortunately it took a few pistons to figure that one out

 

I thought the dragstrip was a novel idea. Was just trying to figure if there was enough length to get up to speed. I have a airbox on my bike, so think that changes things a bit at speed, at least in theory.

 

Yep. I only met Paul once at VIR about 4 or 5 years ago and he had a lot of data logging going on. He, Stu, and Nobi did rolling runs on the dyno in the USGPRU trailer with his bike.

I also use Sunoco 110 interchangeably with C12 and don't notice a difference. My '98 was originally unleaded, but the needle was switched out and I think the unleaded head was cut down some (although the spark plug area looks different than a '97 leaded head, and is way different than the later year unleaded heads - ??).

 

Ahhhhh the Wossner.... I've always gone with HRC. They did have some problems with HRC pistons years ago when a new manufacturer was used, but the problems were worked out in some way and new HRCs have been fine for 5+ years. I'm sure you have read about (or lived) the break in procedure for the Wossners - something like 10 miles below 5Krpm, total cooldown, then 10 miles up to 8K, cooldown, then 10 miles up to 12k, or whatever. I don't have the place to do that, or patience, and by the time you break one in, you have probably spent more than you've saved. And you don't want to spend time at the track doing that... For new HRCs, do 3 heat cycles at home (or next to Broome's RV if you can), warm it up again before practice, take it easy for the first practice session (or first 4 or 5 laps thereof), then let it rip the second practice session.

My dad usually comes to hang out and help and he knows the drill with 2Ts also, so come on out to a race and we can certainly pit crew for you and help in any way. I have a bunch of notes scraped from USGPRU, many from the illustrious Mr. Linders, about RS125 'stuff' that have really helped me and I can send to you if you want.

Matt

 

I trap around 60MPH on my YSR.
60 is about the lowest speed needed to start affecting airbox pressures, depending on bike/system. I think you'll be way over 60.
You could do plug chops, too.